1. Field of the Invention
This invention relates to a load support system for an inclinable structure consisting of two decks which are used to store a vehicle on each deck. The inclinable structure is supported by a fixed axle on one side and two independent cable or hydraulic actuator systems on the other side, enabling the structure to be positioned for vehicle access to either deck.
2. Description of Prior Art
Typical characteristics of prior two-deck inclinable structures are described in U.S. Pat. Nos. 4,486,140, 4,316,527, 3,9840,11, 3,941,257, 3,924,760, 3,786,940, 3,712,485, 3,520,423 and 3,493,129. These structures change shape as they tilt. U.S. Pat. No. 3,520,423 discloses an inclinable structure consisting of two decks which are constrained to move in a parallelogram geometric configuration. Each deck has provisions to store a vehicle. The forces which move the decks plus the stored vehicles are derived from a single hydraulic actuator which, in turn, operates two independent cables which are attached to two locations on one of the decks. This results in a distribution of reaction forces at the two cable attachments and the fixed axle bearings. Thus, each cable supports one fourth (1/4) of the total weight including the empty weight of the inclinable structure plus the combined weight of both vehicles. Should one of the cables fail, however, the surviving cable system is required to support one half (1/2) of the total weight including the weight of the vehicles. Since the empty weight of the structure is a constant, the impact of a cable failure is considerable with regard to the fail-safe vehicle load capacity of the inclinable structure. A similar situation occurs with U.S. Pat. No. 3,941,247 where the forces required to move the structure are supplied by a single electric motor which operates two independent chain drive systems. Here again, failure of one of the chain drives will result in a doubling of the forces on the surviving chain drive. In the case of U.S. Pat. No. 4,486,140, two independent hydraulic actuators are used to obtain fail-safe characteristics. If one of the actuators should fail, the surviving hydraulic system must produce twice the load-carrying capacity it normally supplies. Another disadvantage of the prior art two-deck configurations is the complex linkages required to change the shape of the inclinable structure as it changes position.
A characteristic of the inclinable vehicle storage structures is the requirement to restrain the vehicles from moving when the storage decks are inclined away from horizontal. U.S. Pat. Nos. 3,493,129, 3,520,423 and 3,941,257 recognize the need to prevent movement of a stored vehicle while the structure transitions from one position to other operational positions. This need is met by requiring the vehicle driver to maneuver the front wheels of the vehicle into a depressed wheel well. In the case of Japan document 0192963, the driver is required to feel the automobile climb a ramp and subsequently feel that the wheel has been lowered to its operational position for the device to be effective. A particular disadvantage of the devices used is the extra engine effort required to exit the wheel well. The devices described in U.S. Pat. Nos. 3,493,129, 3,520,423, 3,941,257 and Japan document 0192963 will be ineffective and unsafe if the vehicle driver does not maneuver the vehicle into the wheel well which restrains movement of the vehicle.